Electric signaling system



OCt- 9, 1951 D. s. RIDLER ETAL. 2,570,279 I ELECTRIC SIGNALING SYSTEM Filed April 6, 1949 6 Sheets-Sheet l F f sA sa .sc M02 i' "El I ALLoTTE/zl 2| g55/VG n "1 CONTACTS :i

MARK/NG EAD I;

* I T G=GA5 TUBE TR P j l Q5 31 msm/Euro@ COUNT/N6 TPA/N l F//esr D/G/T STORAGE I v n GROUP l l I CLD* SECOND o/G/T l l-.T- T STORAGE GROUP I (BJ (l THIRD o/G/T STORAGE CHARACTER l GPOUP o/sT/e/Buroa I 16E/ AY CONTACTS Q5' MAPK/N6 6:45 TUBES .1 I GATED 5mn/NW6( u: MARK/NG RELAYS PULsEs 1 I coz/NT/NG PULSE TIME BASE LEAD INVENTORS DES/MND .5. lP/DLEK 'LESLIE R BROWN ATTCRNEY Oct. 9, 1951 D. s. RIDLER ErAL vELECTRIC SIGNALING SYSTEM 6 Sheets-Sheet 5 Filed April 6, 1949 wm S 3.3 NWS@ INVENTORS ESMOA/o s. R/DL ER L ESL/E R- BROWN ATTORNEY Oct. 9, 1951 D. SRIDLER ETAL" ELECTRIC SIGNALING SYSTEM 6 Sheets-Sheet 4 Filed April 6, 1949 E. lo me Y ma. m m? vou n mm EL A o Oct. 9, 1951 D. s. RIDLER ET AL ELECTRIC SIGNALING SYSTEM Filed April e, 1949 6 Sheets-Sheet 5 INVENTORS DESMO/VD S. /DLER LES/E BROWN BY ATTORNEY Oct 9, 1951 D. s. RIDLER ET AL 2,570,279

ELECTRIC SIGNALING SYSTEM Filed April e, 1949 e sheets-sheet e ESL/E @s Brow/v l I BY mat,

ATTORNEY Patented Oct. 9, 41951 ELECTRIC SIGNALING SYSTEM Desmond Sydney Ridler and Leslie Ronald Brown, London, England, assignors to International Standard Electric Corporation, New York, N.- Y.,- a corporation of Delaware l Application April 6, 1949, Serial No. 85,789 In Great Britain April 7, 1348 7 Claims. 1

This invention relates to electric signalling system and its object is to provide improved signal storage means.

The use of storage registers in automatic switching systems generally is well known where, by their use, selection information in one form or another may be stored and subsequently retransmitted in the same or a different form. Considerable operational advantages result from their use in the accuracy and flexibility thereby provided in such signalling systems, and the limitations which formerly were imposed by the necessity to employ mechanical relays in registers, with their attendant disabilities, have been mitigated by previous proposals to carry out many of the functions hitherto performed by relays by means of gas discharge tubes, with consequential circuit simplifications and other improvements, including improved reliability and longer life.

According to the present invention, there is provided a signal storage device for constant total permutation code signals which comprises means for registering successive signal codes on successive rows of gas discharge tubes synchronously with the receipt of such signal codes.

The invention will be particularly described with reference to the accompanying drawing which relates to keyboard selection, but is by no means limited to such an application.

The use of automatic selection signals set up in teleprinter code directly on the keyboard by an operator has considerable technical and operational advantages over dialling or manual selection techniques, and a system will be described herein whereby registers are called in to store the selection signals and to set up a potential-marking scheme for subsequent operation of selector switches. The equipment to be described with reference to the accompanying drawing is in the nature of a model, and is consequently somewhat simplied compared with that required for a fully equipped system.

However, the register, which is the equipment mainly concerned in this description, is much the same whether the system as a whole is simple or complex, and the principles involved are therefore understandable from the workings of such a simplified model.

In the accompanying drawing:

Fig. 1 shows in block diagrammatic form the overall circuit arrangements adapted for the model;

Fig. 2 shows diagrammatically the potential pattern set up in a `storage group for the digit '1;

Fig. 3 shows a hard tube time-base circuit for providing the necessary pulses for controlling the register; and

Fig.` 4 in its several sections, A, B, C, shows a complete register circuit for a three figure selection code.

In the drawings relays have been designated by a letter or letters placed over a horizontal line and having a number thereunder, the number representing the number of contacts which are physically controlled by the relay. These contacts are shown distributed over the various figures in the circuits which they control, rather than in close association with the relays to which they belong. The contacts are designated by the letter or letters of the relay to which they belong followed by a number to differentiate the contacts of the same relay. This arrangement avoids a complex wiring diagram and makes the drawing easier to read and understand.

GENERAL DESCRIPTION Referring now to Fig. 1 of the drawing, the upper portion, above the dashed line, shows the simplified trunking arrangements used in the model. A teleprinter (T/Pl) operator calls in the exchange equipment by depressing a Call key which causes a line finder switch (L. FJ' to associate a connecting circuit with the calling line in the conventional manner for automatic telephone working. Normally an allotter switch (shown in the dashed outline) would be used to associate the register with the connecting circuit, but since only two substations are involved in the model, the allotter has been omitted. A visual audible proceed to keysend signal is returned to the operator who then keys gures shift followed by the called substation number which consists of three digits.

These digits are electronically registered on gas tubes in the register circuit and, after the last digit has been received, a marking group of five gas tubes'examines such storage groups in turn. Five relays in the anode circuits respectively of these five tubes serveto translate the intelligence stored in each group into a marking which is used to set up the selection switches. In a complete exchange system, one of the known multipotential marking schemes would be used, but for this simple case, simple earth marking has been adopted.

The storage tube arrangement comprises a set of ve tubes per digit which, according to whether they are normal or fired (triggered), register respectively a mark or a space.

The standard 5-element permutation code actually comprises seven elements, the characteristic .Fi-element code portion being sandwiched between an initial space and a final mark in all cases. The common initial and final elements are not stored, and hence only ve tubes perk digit are required to store the intelligence contained therein. n

The operation of the register, in outline, is as follows.

The key-sent digits are received on the polarised relay TR, the rst change-over froml niark to space starting the timeba'sainua manner somewhat as described in the United States Patent No. 2,433,362, issued on DecemberQ. 1947, to G. C. Hartley and W. J. Reynolds. This `time base delivers two outputs of pulses known as scanning and-counting pulses respectively, each having a basic periodI of 20 milliseconds and being displaced from'one anotherby 1-0 milliseconds, the pulse width being one-half` millisecond.

The time base runs for seven cycles and is then shut off by .the .diStrbutQ .Which f-.OnbT-Ses principally the bankrof gasntubes numbered I'`1 and the dashed square containing two` relay contact sets. Countingupulses, the first of which occurs 20 milliseconds Mafter the start, drive the distributor gas tube counting train known manner and in consequence, potentials vcorre-` sponding in time to the units of` the received. character are offered from Athe cathode resistances of distributortubes to the corresponding tube of a storage group. At thesame time,scanI ning pulses, which areadmitted through the gate circuit only when relay TR is operated to space, are added to the distributor potentials to'trigger the appropriate storage tubes. Potentials corresponding to the digit 7 are shown in the diagram of Fig. 2, whichis self-explanatory.

Switching between groups as each digit is received is by means of relay contacts, as shown, but wholly electronicmeans car be, and have been, used for this purpose. .4 u

When the last digitA- has been received, the marking gas tubes commence" to Aread ff 4the stored digits in turn. .,Thisiszachieved, by `con; necting the control 4electrodes vof, the marking tubes by means of relay contacts to the anodes of storage tubes of each groupinrsequenme.- YA fanof contacts on these marking relays connects an appropriate one of ten markings to 'a marking lead. The first numericalswitch'SA 'is then driven to a similarly markedoutput. The second and third switches are positioned in theA same Way from information stored on the second and thirdr storage groups respectively. When theconnection is complete, the register isreleasediand communication may commence.

v DETAILED DESCRIPTION The invention will 'now bedescribedin rather more detail with reference to the detailed circuits of Figs. 3 and 4.

Time base` Referring rst to Fig. 3,0thisdshows arhard valve time base circuit basedY on well-known phantastron principles. s (The, ,form7 of timev base generator used is not an essential feature of the invention, and this circuit may be rep laced by any suitable circuit'producing the required pulse trains.

For satisfactory should be examined in the centre of each unit or 4 element period, which is nominally 20 milliseconds in duration. The time base therefore provides one output of positive pulses, known as the scanning output, which has a basic period of 20 milliseconds andvdisplacedl() milliseconds from the start of Athe signal. A secoi'idsimilar output is also available having the same basic frequency but displaced by 20 milliseconds from the scanning output. This is known as the counting output and is used for switching and counting purposes. .p u

The circuit is based on two 10 `millisecond Vphant'astron delay circuits arranged to feed a pulse will cause it to stop.

reception, jteleprinter signals Tube Vl with associated elements comprises one phantastron delay circuit and tube V2 with associated elements comprise'sthefscoiid. The' circuits are normally quiescent withk both valves taking screen current. Ifa 4negative starting pulse is` applied to terminal TTll, theranodef'f Vl is driven instantaneously negative through the diodes V3- and V4 and the characteristic reduction of anode volts observed in the phantas'trn takes place. After 10 milliseconds a negative pulse derived from the screen of VI is applied to the anode of V2 through th'e diode V5. The sec,- ond delay circuit is thusbroughtinto operation and, after a further lrnilliseconds delay, apulse is again applied to the anode of V'l through V6 and the cycle is repeated'. In order to stop the time base, a positive potential isappliedto terminal TT. This 'so biasses the diode V6 so that the next screen pulse from V2 is `prevented from triggering Vl once ag'a'in and the time ibase vcomes to rest. Two double trio'd'es (V and V8) are used in their separate sections for pulse shaping and forgiving low impedance cathde follower out-'- puts for the two sets of pulses respectively in known manner.' Means are also p'rvidedvia TT3 for suppressing scanning vpulses'by "an earth from Athe line'vconditin if required. Terminal TT3 is connected to the lrece'id/ing relay contact and is normally rnairitairned` at a Yhigh positive potential so that diode V9 lnonconducting and pulses pass forward fromthe section an"- ode of V1 via condenser VCl to the lfgrid `'offtlie cathode follower section. 'If an earth potential is applied by the contact to TT3, however, ari-'y pulse is short' circuited andnooutput isdeveloped across thecathode resistance. y l Y,

Fille adjustments 't0 tlilf-pas@` 'spetjroarl made by means of Variable'resis'tance R1.` The position intime of'ne pulse with respect to 'the other may be adjusted bylileans'of Vthe `lafriisffed variable resistors R2 R3. y

The pulse width is about 1/2 `nillisec`ond This gives suiiicient time for4 the operation bf 'glas tubes and representsthe iunit scanning time. Greater distortion can thus be allowed fon coming signals thann in thewniechancal ycase where the scanning time'is normally a few milliseconds.

The signal storage :crctccinprses Fig'sfiA and 4B intended to be 'placed one "above"`th"e other, in that order.. V It is necessary f'orthere'gister `to guard' a' rainsi: rane signals which ihigiitccurffr st'rce'u l rig. 4A shows the relevant part of the register' circuit. Polarised relay TR is connected to the substation teleprinter` through the allotter, when provided, connecting circuit, line. finder switch and subscribers line. Proceed to keysend signal is sent back from the connecting circuit and the operator then keysends iigures shift followed by three digits. sumed for the purpose of description that these digits are '719.

The unit distributor counting train is a scale` of seven counter consisting of gas tubes TDAI-'I. The character distributor counting train is a scale-of-four counter consisting oi tubes TDBI-4, extending vertically downwards into Fig. 4B.

Before seizure, the first tubes in each counting train TDAI and TDBI are triggered over contacts B3 and B2 respectively of a relay B (not shown), manner on seizure of the register. All other tubes are normal. The operation of B relay on seizure removes the triggering potential at B2 and B3, and frees the distributor trains. When a character is received, the flrstchangeover to space of relay TR at TRI dischargesto earth the condenser CI in the TT4 start lead and thereby creates a negative pulse to start the time base, Fig. 3, in the manner previously described. Counting pulses received over lead TTI drive the unitV distributor train from` TDAI to TDA? in well-known manner, each tube as it lires sending a pulse out, priming Jche next tube and extending the previous tube, as described, for example, in United States Patent No. 2,421,005, issued on May 27, 1947 to F. I-I. Bray and L. R. 'Brown and a positive gating potential is applied from the cathode of TDAI via TTS stop lead to stop the time base. The `iinal pulse triggers tube TDAI and restores the train to normal. The cathodes of tubes TDA2-6 are connected to other tubes via voltage limiting rectiers for priming functions.

The rst character to be received should be figures shift which is SMMSMMM. Tubes TGD and TFG are used to check the reception of this character. Priming potentials are applied from the cathodes of tubes TDA2, 3, 5 and 6 to tube TGD via the coupling rectiers MRS-MRS. The timing of these potentials corresponds to the timing of the second, third, fifth and sixth mark units. At the same time, scanning pulses are applied over the lead from terminal TT2 (Fig. 4B) to the i'lrst character distributor RI-R3, and condenser C2. This gate circuit allows a pulse to pass to the trigger electrodes of TFG and TGD only when the controlling tube TDBI is conducting and MRI is a high resistance.

When tube TDBI is conducting the cathode end of R3. which is a high resistance, is at high Let it be .as-

which operates in well-known positive potential, thus biasing MRI strongly positive on its positive side and causing it to present a high resistance to positive pulses on its negative side. The pulses are therefore gated ofi to the right, to tubes TFG and TGD.

Conversely, when TDBI is normal, the positive potential on MRI is very low, or earthy, and positive scanning pulses are easily shunted away to earth via MRI instead of going in the other direction.

Tube TGD will trigger only when a primingA potential and a scanning pulse are applied at the same time. Since scanning pulses are normally suppressed by contact TRI in the mark condition via lead TTS, as explained in the description of the time base circuit, it follows that if there is a space (where there should be a mark) among the second, third, fth or six-th units, tube TGD will trigger and operate guard relay GD to disconnect the circuit for relay FG. For similar reasons tube TFG will trigger only if the centre unit is a space and relay GD has not already operated. The operation of relay FG can only be` maintained by the gures shift character. All the other characters except letters shift (S.MMMMM.M) will eventually operate the guard relay GD and so disable relay FG and the operator must clear down and recall the exchange to set up a connection. Letters shift does not fire tube TGD, but, on the other hand, neither does it rire tube TFG and the register must still await a figures shift signal before storage can proceed.

If the first character has been satisfactorily checked by the operation of FG relay, contact FGI, Fig..4B, removes a short circuit from the priming lead of the character counter and a counting pulse applied via TTI and gated by the last unit distributor tube TDA'I when in the triggered condition, triggers tube TDBZ. Further scanning pulses will thus be switched to the rst storage group of tubes TSAI-S through the gate circuit comprising MR2 and associated components.

The second character, which is the first numerical digit, starts the time base in the same way and the unit counter runs as before. Priming potentials are applied in turn to each storage tube corresponding in time to the second, third, fourth, fth and sixth signal units. If the contact of TR relay is at mark during priming the tube remains normal. If the contact is at space, a scanning pulse is admitted and the primed tube triggers. For digit seven (SMMMSSM) the tubes TSAI, 2 and 3 remain normal and TSA4 and 5 trigger. As before, a counting pulse Ais switched to the character counter at the end of each cycle of the unit counter. Thus tube TDB3 is triggered and the second storage group is prepared for the second digit. This is stored in a similar way on tubes TSBI-. The third digit is stored on tubes TSCI-5.

Finally tube TCD triggers having been primed by tube TDB4 to operate relay CD. Contact CDI disconnects further scanning pulses and contact CD2 disconnects relay TR. The selection information is now stored on the storage group of tubes and the register is ready to set up the connection.

Marking circuit adware,

These potentials,

In this way the lcomplementary pattern, e. g. in the case of digit seven, storage tubes TSAI, 2 and 3 were normalY and TSA4 and 5 triggered. On transfer thel marking tubes TMAl, 2 and 3 conduct, and TMAQ' and 5 remain normal. Five relays. ON, TW, TH, FO, and FI, one in the anode of each tube, opf-y erate inV the same combination. A fan ofv contacts of Vthese relays connects onel of ten `dis crete marking potentials to a marking lead which is, in turn, connected by the allotter switch to the connecting circuit. The closure of CD3 starts the rst selector switch hunting for a similar marking potential on the switch bank as is com- Vmon in potential marking systems.

When the first switch has been positioned, relay RA is released and relay RB is operated to enable the marking tubes to examine andtranslate into a potential marking the Ycode on the second storage group of tubes TSBI-S. The transfer from RA to. RBandthe de-.ionisation of the tubes TMAI-5 is effected by relay switching inra conventional manner not really relevant to the functioning of the register and marker as such.V The second selector switch is positioned through the medium of the marking lead in the same way as the rst. Relay RB .is then released and relay RC is operated andthe third storage group is rexamined. The third switch is positioned and the connection established. At this stage, the register .would normally be released and the allotter switch would be free to find another connecting circuit for the purpose of setting upjanother call.

In any practical circuit, the functions of the mechanicalv relays shown could in many or all cases be replacedby gas tube relays; Athis applies` particularly to the RA, RB and RC relays.

The extremely simple gate circuits provided and the figures shift check circuit offer considerable advantages and safeguards over earlier circuits.

Also the use of a short scanning vpulse of the order of one-halfwmillisecond increases the dis--v tortion margin which can be allowed on incoming signals to extremely high values. In the case of the model described the theoretical distortion that can be allowed'on the TR contact is48.75f%, a figure perhaps impossible to achieve in api-ac-V tical mechanical systern, while the speed -variation in the hard'tube time base is less than-0.5% for a wide range of operating voltages, and it is anticipated that a much'better figure than this may be achieved in future designs.

While the principles ofthe inventionhavebeen described above in connection with specific embodiments,y and particular modifications thereof?, it is to be clearly 'understood that this description is made only by way of example, and not asa limitation on the scope of the'invention.

What is claimed is:

1. A signal storage device for constant total character c'ode being deined as; one cedette rangement of signals in the constant total perv mutation code and mdicative of that characterf e. g. MMMSS for the character 7 in a -unit code), a row of character code distributor tubes arranged to` distribute the received character codes in order among the said rows of register tubes, means for rendering the register tubes ay row synchronously responsive to` pulses representative. of the character code being received, thereby to ire or to maintain uniired such tubes according to the nature of such code, means coupled between said bank of character code register tubes and the first Qf" said character code distributor tubes responsive only to a particular andV predetermined; character code of dissimilar elements, thereby to allow or prevent the registration of succeeding;

character codes according to the first character code actually received, and means to change., all; the end oi thestorage of each character code'as, it is received. the condition of the next tube, the row of character code distributor tubes, thereby to direct the pulses representative oi ther next received character code into the next register row.

2. A signal storage device as claimed in claiml 1 and in which the said first-named means comprises a time-base generator for generating in-4 terlaced trains of equally spaced pulses, eachv train thereof having a spacing equal to. that V,of the nominal spacing of the character codes to be stored, and the first train thereof being ini-` tiated under the control ofl the iirst element of permutation code signalswhich comprises abank a received signa] comprising at least a start ele--` ment and a character code, whereby each tube in a register row may be primed in turn synchronously with the elements `of a received chars acter code by means of the first, or countingt train of pulses Ain preparation for the reception of pulses from the second, or scanning train of pulses transmitted to such register row, or .supe pressed, in accordance with the elements of the character code being received.

3. A signal storage device as claimed in claim 1 and comprising a train of counting tubes adapted to be red and quenched in turn by the said first train of pulses, thereby to provide pulses for priming the tubes in the said register rows and the said character row in due order. Y

4. A signal storage device as claimed in claim 3 in which said tube condition changing means comprises the priming pulse generated in the last tube of the said train of counting tubes by each discrete train of counting pulses.

5. A signal storage device for constant total permutation code signals comprising a bank of gas discharge tubes arranged in rows of character code register tubes, each row being responsive to one character code to be stored, a row of character codedistributor tubes arranged to dis tribute the received character codes in order among the said rows of'register tubes, means for rendering the register tubes in a row synchr nously responsive to pulses representative of the character code being received, thereby to fire or to maintain unred such tubes according to the nature of such codes, a pair of gas discharge tubes, each coupled to a different one of said character code register tubes and theV first o'f said character code distributor tubes, each of the tubes otsaid pair adapted to be primed-'fromiits associated character code register tube, control means associated in -the discharge path of the first of said pair oftubes, said control means adapted to control operation of the second of said pair of tubes, whereby operation of said first character code distributor tube is under joint control of said pair of tubes and the distribution of succeeding character codes by said character code distributor tubes is dependent upon receipt of said character code register tube of a predetermined character code of dissimilar elements, and means to change, at the end of the storage of each character code as it is received, the condition of the next tube in 'the row of char acter code distributor tubes, thereby to direct the pulses representative of the next received char acter code into the next register row.

6. A signal storage device for constant total permutation code signals as claimed in claim 5, further comprising a gate circuit coupled between said pair of tubes and the rst of said character code distributor tubes, said gate circuit comprising a rectifier biased by a potential derived from a current flow in the first of said character code distributor tubes, whereby" a high resistance is presented to the first of said pair of tubes and rendering effective pulses applied to the rst of said pair of tubes to re same in accordance with the predetermined character code.

7. A signal storage device for constant total permutation code signals as claimed in claim 5, further comprising a plurality of gate circuits, each of said gate circuits comprising a poled rectifier, one associated with each of said character code register tubes, selected of said gate circuits coupled to the iirst of said pair of tubes, another of said gate circuits coupled between another of said character code register tubes and the second of said pair of tubes.

DESMOND SYDNEY RIDLER. 'LESLIE RONALD BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,193,967 Kleinschmidt Mar. 19, 1940 2,456,825 Fitch et. al Dec. 21, 1948 2,465,355 Cook Mar. 29, 1949 

